1. Field of the Invention
The present invention is directed to a light rail vehicle with a predictive diagnostic system for a motor driven automated door system. The diagnostic system monitors the automated door system to enable condition-based maintenance.
2. Description of the Prior Art
A motor driven automated door system of a light rail vehicle is an electromechanical system that degrades over time. Currently, the automated door system requires labor-intensive preventative maintenance in order to ensure high reliability. This xe2x80x9ctime-basedxe2x80x9d maintenance approach results in the system and its components being maintained even when there is no need for maintenance, resulting in high maintenance costs, ineffective use of maintenance resources, and significant downtime.
It is an object of this invention to provide an alternative to scheduled preventative maintenance of a light rail vehicle automated door system that will reduce maintenance costs and increase maintenance efficiency while maintaining or increasing the availability of the automated door system.
Accordingly, we have developed a predictive diagnostic system for use with a light rail vehicle automated door system to monitor the door system and identify when maintenance is necessary based on measured door system conditions. The predictive diagnostic aspect of the present invention requires knowing normal and failure door system conditions, determining current state door characteristic deviations, calculating rate towards failure conditions, and invoking maintenance before failure conditions occur.
As the automated door system operates, weather conditions, foreign substances in the path of the doors or in the door tracks, normal wear of components through friction and stress, people holding the doors open, etc. cause degradation of system components, such as the electrical motor, levers, rollers, and/or tracks. This degradation leads to failures, such as improper opening and closing of the door, worn out rollers, a bent operator arm, and a worn out operator arm track. These failures increase the frictional resistance against the door, causing the motor to work harder. Therefore, the effect of friction on the door is an important diagnostic parameter for the automated door system.
The predictive diagnostic system for the automated door system of a light rail vehicle according to the present invention monitors the motor driven door system and determines its current health and rate of degradation. During operation of the door system, several parameters are checked for characteristic deviations that indicate an impending system failure. Deviations are detected by comparing the current state of the parameters to past parameter values, whereby the current health and the rate of degradation of the door system are determined. From the rate of degradation and a known point where the system requires maintenance, a predicted time to failure can be determined. In turn, an indication of the required maintenance can be provided, thereby avoiding unnecessary preventative inspection of healthy equipment.
The diagnostic system, therefore, is able to predict door system failures far enough in advance so that the required maintenance can be performed during scheduled maintenance periods. The benefit of using predictive diagnostics is that the automated door system will not be over-maintained, but rather maintained only when necessary, resulting in a reduction in degradation-type failures, a reduction in maintenance costs, an increase in maintenance efficiency, and an increase in system availability.